[stable/yoga] Adding fixing broken configuration test for mysql-router

[xtrusia]

(cherry picked from commit 0a8889796605d33315e7fed93743c21eba1d2c6b)

[ajkavanagh]

Note: stable/caracal, stable/bobcat, stable/antelope and stable/zed all require this cherry-pick for consistency. Otherwise, odd things may happen if testing with say stable/antelope.

[xtrusia]

Note: stable/caracal, stable/bobcat, stable/antelope and stable/zed all require this cherry-pick for consistency. Otherwise, odd things may happen if testing with say stable/antelope.

Thanks a lot. I created PR

1219 #1220 #1221 #1222

[ajkavanagh]

Note that: https://review.opendev.org/c/openstack/charm-mysql-router/+/921716 is using this PR; don't delete the branch until that review has merged.